Henri Poincaré, Quanta hypothesis: Conclusions

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We see what is the state of the question; the ancient theories, which hitherto seemed to account for all known phenomena, have encountered an unexpected obstacle. It seemed that a modification was necessary. A hypothesis was first presented in Mr. … Read More

Henri Poincaré, Quanta hypothesis: The new theory of Planck

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Let us go back to less general and more precise problems, for example to the theory of radiation. Mr. Planck has devised an amendment to his first theory, and I would like to say a few words about it. According … Read More

Henri Poincaré, Quanta hypothesis: Quanta of action

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The new design is seductive by a certain side; for some time the tendency has been to atomism, matter appears to us as formed of indivisible atoms, and the electricity is no longer continuous, it is no longer divisible to … Read More

Schrödinger equation

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Schrödinger equation, developed by the Austrian physicist Erwin Schrödinger in 1925, is a fundamental equation in quantum mechanics. It describes the evolution over time of a massive non-relativistic particle, and thus fulfills the same role as the fundamental relation of … Read More

Quantum states

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The state of a physical system describes all aspects of this system in order to predict the results of the experiments that can be performed. The fact that quantum mechanics is non-deterministic leads to a fundamental difference compared to the … Read More